There are not many aspects of web design that seem to ignite the same fascination in developers as making elements dynamic by hiding and showing them on user interaction. Collapsible lists, maps with hover elements and multi level drop-down navigations still seem to be hot and need to be part of a web site to make it "cool" and to "increase usability". Much like the magician conjuring the rabbit out of the top hat for the tenth time in a row, this design stunt does gets a bit stale though. Maybe it is time to take a step back and look at what we do.
Dynamic Page Elements-Cloak and Dagger Web Design - Collapsible Page Elements (Page 7 of 10 )
One less common use of dynamic elements is to only show and hide certain parts of the page, for example a right hand extra navigation or additional information in a list of products.
Unless we add extra information this way, we don't have a case of content overload. The only remaining things to keep in mind are:
1. Not maintaining the current state
Once users have chosen to hide or show a certain page element, they should not have to repeat their decision on each following page. We should ensure the state is kept in a cookie or some other mean of data storage.
2. Jumpy display
Unless we show and hide the element via including it or not on the backend, there will be a brief moment when the element is visible before it gets hidden. This is nothing serious, but users can be confused and annoyed.
3. Unknown functionality
We need to tell users that they can hide and show this part of the page, or that there is extra information.
Design Usability 
HTML5 Boilerplate Introduction
